Isolators are known devices that are installed on engine crankshafts and on accessory drive shafts for reducing the transmission of torsional vibrations from the crankshaft to a belt driven by the crankshaft. During a key start event (i.e. an event where the engine is being started by its starter motor), the engine is driven up to a speed of a few hundred RPM by the starter motor, fuel is introduced into the cylinders and is ignited. The engine then ramps up its speed from the initial speed where ignition first took place to an idle speed. In some instances, the engine passes through a speed where resonance can be significant.
It would be beneficial to provide an isolator that is configured to isolate one or more driven accessories from torsional vibrations that take place during such resonance or from other situations where there is a high torque transfer.
Additionally, while a traditional isolator is useful in many vehicular applications, some isolators do not perform ideally in applications wherein the belt is sometimes used to transmit torque to the crankshaft, for example as part of a Belt-Assisted Start (BAS) drive system wherein an electric motor is used to drive the belt in order to drive the crankshaft for the purpose of starting the engine.
It would be advantageous to provide an isolator that is configured for use in vehicles with BAS drive systems or the like.